The present invention generally relates to a process for satisfying the nutritional requirements of ruminants for methionine, and more specifically, to a process for meeting those nutritional requirements using the hydroxy analog of methionine (2-hydroxy-4(methylthio)butanoic acid) and its salts, amides and esters.
High producing dairy cows need methionine, lysine and other key essential amino acids to reach their genetic potential for milk production. While amino acids can be added directly to the diets of monogastric animals to overcome nutritional deficiencies, free amino acids are rapidly degraded by rumen bacteria and are of little or no practical benefit in alleviating amino acid deficiencies in ruminants.
Traditionally, undegradable intake protein ("UIP") such as blood meal, fish meal, corn gluten meal and others have been used to provide essential amino acids to ruminants. It is difficult, however, to accurately deliver needed levels of methionine and other essential amino acids without providing excess levels of other non-essential amino acids and, any excess nitrogen which UIP delivers to the rumen must be degraded and eliminated by the animal. Consequently, formulating feeds which satisfy the methionine requirements using UIP sources is not only expensive, it can also affect cow health and productive status.
As an alternative to UIP, attempts have been made to modify or protect methionine in a manner so that it is not susceptible, or at least is less susceptible, to rumen degradation. Various "coatings" for methionine have been proposed which, in theory, enable the rumen protected methionine ("RPM") to clear or "bypass" the rumen without significant destruction by rumen microflora and deliver this key amino acid to the small intestine. Once in the small intestine, the coating dissolves thereby freeing the methionine which is absorbed from the intestine.
The practical application of rumen protected methionine, however, has presented some challenges. For example, some products have limited solubility. For others, pelleting, expander conditioning, mixing, and other normal milling practices fracture the protective coating, making the methionine molecule vulnerable to rumen degradation. Some dairy producers have circumvented this problem by top dressing the rumen protected methionine on final rations. This labor intensive practice, however, does not allow the ingredient to be uniformly distributed in the diet. As a result, cows within a herd may consume different amounts of methionine.
It has been reported that the milk production of dairy cows can be increased by supplementing the diets of the cows with the hydroxy analog of methionine and its salts and esters. See, e.g., U.S. Pat. No. 4,388,327. Previous attempts to implement this technology, however, were met with unpredictable milk production responses.
More recently, the calcium salt and the free acid forms of the hydroxy analog of methionine have been combined with bypass fats in a dry product for use as an ingredient of a ruminant food ration. As understood, the level of inclusion of the bypass fat/hydroxy analog dry product has been determined using a computer model which matches the nutritional requirements of the ruminant with available feed ingredients. This approach, however, suffers from several disadvantages. Because the two ingredients are combined in a predetermined ratio, the product offers less flexibility in formulating a ration which meets a least cost objective and precludes the possibility of formulating a feed ration which includes the hydroxy analog of methionine but not bypass fat. In addition, the dry form of the product is susceptible to the formation of undesirable dust and to non-uniform mixing with other feed ration ingredients.